Managing Irrigation Sediment Barriers in a Tropical\nVolcanic Basin through Mathematical Model

Volcanic eruptions\ntransport substantial amounts of sediment into\nriver systems. It damages irrigation structures that depend on the\nnearby river for water delivery, reducing the conveyance efficiency.\nThis study aims to propose an efficient approach for the management\nof sand traps as the main sediment barriers in irrigation networks\nwithin the Progo-Opak-Serang (POS) Volcanic Basin. It is accomplished\nby a measurable approach: a mathematical framework executed with the\nHydrologic Engineering Center’s River Analysis System (HEC-RAS).\nThis study focuses on selected sand traps: Badran, Blawong, and Pengasih.\nThe results show that the calibrated and validated Manning’s\ncoefficients of Badran, Blawong, and Pengasih Sand Traps are 0.014,\n0.020, and 0.025, respectively. The combination of Thomas as a sorting\nmethod, Rubey as a fall velocity method, and Laursen as a transport\nfunction can represent the transport parameters of the sand traps\nwithin the POS Basin. The recommended flushing discharge and duration\nfor Badran, Blawong, and Pengasih Sand Traps are 4, 4.4, and 1.9 m<sup>3</sup>/s and 150, 50, and 45 min, respectively, while the flushing\nfrequency is 4, 3, and 3 times a year. The existing sand trap performance\nin Badran is less effective, while that of Blawong and Pengasih is\nless efficient. This study assists in improving food production and\nsecurity by promoting sustainable irrigation systems.